<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        *{margin: 0;padding:0}
        .small-icons img{
            width: 116px;
            height: 116px;
        }
        .current{
            border:2px solid red;
        }
        .content img{
            height: 500px;
            width: 600px;
            border: 2px solid red;
        }
    
    </style>
</head>
<body>
    <div class="small-icons">
        <img src="images/01.jpg" alt="" class="current">
        <img src="images/02.jpg" alt="">
        <img src="images/03.jpg" alt="">
        <img src="images/04.jpg" alt="">
        <img src="images/05.jpg" alt="">
    </div>
    <div class="content">
        <img src="images/01.jpg" alt="" class="current">
    </div>
    <script>
        var icons=document.querySelectorAll(".small-icons>img");
        var show=document.querySelectorAll(".content>img")[0];  //类似数组的对象 所以在后面要放一个[0]
        for(let i=0;i<icons.length;i++){
            icons[i].index=i;   //为了拿到下标
            icons[i].onclick=function(){
                for(let i=0;i<icons.length;i++){
                    icons[i].classList.remove("current")
                }
                this.classList.add("current")
                var index=this.index;
                show.src=`images/0${index+1}.jpg`
            }
        }
    </script>
</body>
</html>